1. Field of the Invention
The present invention relates to a gas injection device having check valve.
2. Description of the Prior Art
A proper amount of ozone has the function of sterilization, deodorization and anti-oxidation; therefore, there are many ozone-adding devices in the market. The ozone-adding devices can be assembled on faucets to add ozone into the water in the tube.
Generally, the ozone-adding device disclosed in TW M365537 includes a venturi tube, and a hole is formed on a narrower part of an inner diameter of the venturi tube. The hole is connected with a gas-providing device. Through the effect of the venturi tube, gas is sucked and mixed with water, wherein the gas-providing device or gas manufacturing device are usually sensitive to water, if water flows reversely to the gas-providing device, the gas-providing device may be damaged. Therefore, a check valve is often disposed between the gas-providing device and the venturi tube to prevent water from flowing reversely to the gas-providing device.
The check valve disclosed in the above-mentioned prior art is normally closed, that is, gas provided by the gas-providing device has to overcome elasticity of an elastic member and push away a rolling bead so as to enter the venturi tube. Check valve which is normally closed has better non-return effect; however, gas needs to have proper pressure to push away the rolling bead. When the gas pressure is lower, gas cannot enter the venturi tube, and valve bodies with rolling bead cannot effectively prevent gas from leaking completely.
The present invention is, therefore, arisen to obviate or at least mitigate the above-mentioned disadvantages.